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• ffmpeg scaled output resolution is off by 1px for non-standard inputs [duplicate]

  14 janvier 2023, par GROVER.

  I'm using the ffmpeg CLI to scale user-submitted videos :

  


  ffmpeg -i path/to/file -vf scale=1920:-2 -c:v libx264 -r 30 output.mp4


  


  The scaling works fine with standard video sizes, such as 1920×1080 and 720×480. However, once we start using videos that do not have conventional resolutions, the output begins to scale incorrectly.

  


  For example, a video that has a resolution of 3360×1882 will output to 1921×1076, when the expected resolution should theoretically be : 1920×1075.

  


  Now, obviously ffmpeg is attempting to account for that remaining .42857px on the height, but I'd prefer it just get cropped off instead (doesn't matter if it's from the top or bottom).

  


  How would I go about doing this safely for every video ?

  


  For bonus points, how do I make it swap scaling depending on if the height is greater than the width (and vice versa). For example, if the video has a ratio of 2:1, it scales using a height of 1080px instead of a width of 1920px.

  


• How to stich images into a video with resolution larger then 4K using FFMPEG ?

  14 janvier 2023, par Aviram Fireberger

  I have a folder with images that I've extracted from one video.
The resolution for each image is 5760 X 2880.
All images are in the following format :
out-1.jpg, out-2.jpg , out-3.jpg ..... out-1000.jpg

  


  I tried couple of different ways to stich them :

  


  Using CPU - libx264

  


  ffmpeg -r 30 -f image2 -s 5760X2880 -start_number 1 -i "AllFrames/out-%d.jpg" -vframes 119 -vcodec libx264 -crf 25  -pix_fmt yuv420p "/AllVideoChunks/Chunk_1.mp4"


  


  Worked well but the speed is about X0.05 only.

  


  Using GPU - h264_nvenc

  


  ffmpeg -r 30 -f image2 -s 4000X2000 -start_number 1 -i "AllFrames/out-%d.jpg" -vframes 119 -vcodec h264_nvenc -gpu  0 -preset slow -b:v 75M  -pix_fmt yuv420p"/AllVideoChunks/Chunk_1.mp4"


  


  Working very fast and high quality, but the problem is that I can't use it for images and output bigger then width 4096

  


  Using GPU - hevc_nvenc

  


  ffmpeg -r 30 -f image2 -s 5760X2880 -start_number 1 -i "AllFrames/out-%d.jpg" -vframes 119 -vcodec hevc_nvenc -gpu  0 -preset slow -b:v 75M  -pix_fmt yuv420p"/AllVideoChunks/Chunk_1.mp4"


  


  Working X10 more then the CPU at the speed of X0.5, good quality, but the problem is that I can't use it in normal players (can't play it in Unity)

  


  Is there another video codec that can work on GPU that support more then 4K resolution ?
Can I transform the 'hevc_nvenc ' output to 'h264' on GPU in higher resolution ? should I do this transformation on CPU ?

  


• FFmpeg script for linux and windows batch video encode different settings depending on video resolution [closed]

  28 décembre 2022, par Jaroslav Havel

  I'm looking for advice, help. I would like to convert all home videos to H265 using ffmpeg. Videos are in different formats and resolutions (3GP, mov, avi, mpg, mp4). I have an idea of which setting to set for which resolution, but I don't know how to write it all into a script (windows and linux). For these resolutions

  


  CRF 18-22 for <= 576p use 20
CRF 19-23 for > 576 and <= 720p use 21
CRF 20-24 for >720 and <= 1080p use 22
CRF 22-28 for >= 2160p 4K use 25


  


  For windows i have

  


  @ECHO OFF

FOR %%F IN ("*.*") DO (
     ffmpeg -i %%F -c:v libx265 -crf 20 -preset faster -profile:v main -pix_fmt yuv420p -acodec libmp3lame -b:a 192k %%~nF_new.mkv
)


  


  Big thanks for the help